Micro robots built by researchers for medical purpose. Here the complete news:
Artificial bacterial flagella are about half as long as the thickness of a human hair. They can swim at a speed of up to one body length per second. This means that they already resemble their natural role models very closely.
They look like spirals with tiny heads, and screw through the liquid like miniature corkscrews. When moving, they resemble rather ungainly bacteria with long whip-like tails. They can only be observed under a microscope because, at a total length of 25 to 60